The U.S. military abruptly canceled the deployment of more than 4,000 troops to Poland and announced it would withdraw 5,000 troops from Germany as the department restructures its posture in Europe.

The canceled deployment to Poland, which was reported on Wednesday, involved the 2nd Armored Brigade Combat Team, 1st Cavalry Division, also known as the “Black Jack” brigade, based at Fort Hood, Texas. There was no immediate explanation for the decision.